The Determination of Longitude. | 401 
The method of work adopted was that observations at all 
stations should be made at the same time. The time ex- 
changes were carried out in such a way as to practically 
give two clocks at each station. Using Greenwich time 
an exchange was made between Greenwich and Waterville 
at 8p.m., andagain at 12 midnight. The cable exchange 
was made at 11.45 p.m. Between Hazel Hill and Montreal, 
exchanges were made at 1130 p.m., and 2.30a.m. The 
cable exchanges, therefore, came in between the iand line 
exchanges, and near to neof them. The clocks in the 
fixed observatories at the terminal stations were available 
as a check on the rates of the cable station clocks. Un- 
fortunately the reductions of this work are not at the pre- 
sent time sufficiently far advanced to justify any public 
statement as to results. 
In the previous trans-atlantic longitude determinations 
to which reference has been made, there was no interchange 
of observers and the telegraphic facilities were compara- 
tively imperfect. Owing to the liberality of the British 
and Canadian Governments we were in this work able to 
meet the expense involved in the exchange of observers, 
and through the generosity of the Commercial Cable Com- 
pany and the Canadian Pacific Telegraphic Company, an 
unrivalled telegraphic connection was obtained between the 
stations. Any reference to our indebtedness in connection 
with this work is not complete without a record of the 
great assistance given by Mr. Hosmer and his staff of assist- 
ants here, by Mr. Dickenson, the able superintendent of the 
Cable Company at Hazel Hill, and his chief assistant, Mr. 
Upham. And beyond the Atlantic, our thanks are due 
to Mr. Wilmot, the superintendent at Waterville, and to 
Mr. Bambrige in London, the European representative of 
the Company. 
Of methods other than the telegraphic, the chief one is 
that depending upon the transportation of chronometers. 
This is the method almost exclusively employed in naviga- 
tion. The error of the ship’s chronometer with respect to 
Greenwich time and its rate, being known when the ship 
